<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>复杂布局</title>
</head>

<style>
     .nav {
            display: flex;
            width: 100%;
            height: 600px;
            background-color: lightgray;
            flex-direction: column;
            align-items: center;
        }

      .item1,.item2,.item3,.item4,.item5{
        margin-bottom: 20px;
      }

      .item1 {
            width: 200px;
            height: 200px;
            background-color: lightblue;
        }

      .item2 {
            width: 300px;
            height: 100px;
            background-color: lightgreen;
        }

      .item3 {
            width: 150px;
            height: 150px;
            background-color: lightyellow;
        }

      .item4 {
            width: 250px;
            height: 120px;
            background-color: lightpink;
        }

      .item5 {
            width: 180px;
            height: 180px;
            background-color: lavender;
        }
</style>
<body>
    <div class="nav">
        <div class="item1"></div>
        <div class="item2"></div>
        <div class="item3"></div>
        <div class="item4"></div>
        <div class="item5"></div>
    </div>
</body>
</html>